Field of the Invention
The present invention relates to a thin-film transistor substrate which can improve the characteristics of thin-film transistors and a display device comprising the same.
Discussion of the Related Art
With the development of information society, various demands for display devices for displaying images are on the rise. In the field of display devices, flat panel display devices (FPDs), which are thin, light, and can cover a large area, have been rapidly replacing bulky cathode ray tubes (CRTs). Flat panel display devices include liquid crystal display devices (LCDs), plasma display panels (PDPs), organic light-emitting display devices (OLEDs), electrophoretic display devices (EDs), etc.
Among these types of display devices, organic light-emitting displays are a self-luminous device, and have fast response time, high light emission efficiency, high luminance, and wide viewing angle. Especially, organic light-emitting displays, which take advantage of the characteristics of OLEDs with excellent energy efficiency, can be classified into passive-matrix organic light-emitting displays and active-matrix organic light-emitting displays. An active-matrix organic light-emitting display comprises a thin-film transistor substrate on which a plurality of pixel areas are arranged in a matrix, with each pixel having one or more thin film transistors.
Each thin-film transistor on the thin-film transistor substrate is formed on a substrate such that a semiconductor layer and a gate electrode face each other with a gate insulating film placed between them, and comprises a source electrode and a drain electrode that are connected to the semiconductor layer. Thin-film transistors are switched on/off by adjusting carriers moving to a channel in the semiconductor layer through the source and drain electrodes by tuning the voltage at the gate electrode. Accordingly, thin-film transistors are affected by surrounding voltages, static electricity, etc., which may change the characteristics of the thin-film transistors.